Production of semicrystalline parts from pseudo-amorphous polymers

ABSTRACT

A method of manufacturing a semi-crystalline article from at least one pseudo-amorphous polymer including a poly aryl ether ketone, such as PEKK, including a softening step, wherein the at least one pseudo-amorphous polymer is heated to a temperature above its glass transition temperature to soften the polymer, and a crystallization step, wherein the at least one pseudo-amorphous polymer is heated to a temperature between its glass transition temperature and melting temperature, the pseudo-amorphous polymer being placed on a mold during either the softening step or the crystallization step before at least some crystallization takes place. The method results in articles demonstrating increased opacity, increased crystallinity, increased thermal resistance, improved chemical resistance, and improved mechanical properties over articles formed by traditional thermoforming processes.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. Ser. No. 16/710,163, filedDec. 11, 2019 which is continuation in part of International ApplicationNo. PCT/2018/037538, filed Jun. 14, 2018, which claims priority to U.S.Provisional Application No. 62/519,906, filed Jun. 15, 2017, the entiredisclosures of which are incorporated herein by reference for allpurposes.

FIELD OF THE INVENTION

The present invention provides articles comprising a poly(aryl ketone),such as polyetherketoneketone (PEKK), and associated methods of makingthe same by thermoforming processes.

BACKGROUND OF THE INVENTION

High temperature thermoplastic polymers, such as polyaryletherketones(PAEKs), are continuously being evaluated as options in a multitude ofapplications, including those in the aerospace and integrated circuitindustries. In general, PEKKs feature exceptional characteristics,including high-temperature and chemical resistance, very good mechanicalproperties, excellent abrasion resistance, and natural flame retardancy.PEKK parts may be produced by a multitude of processes, includingthermoforming processes. PEKK parts formed by traditional thermoformingprocesses, however, may not demonstrate a desired resistance todeformation, among other properties.

The process of thermoforming is a routine manufacturing method. Intraditional thermoforming, a plastic sheet is heated to a hightemperature and placed in contact with a cold (or room-temperature) moldto form a desired shape. When an amorphous or pseudo-amorphous sheet isthermoformed by such traditional thermoforming methods, the thermoformedpart is rapidly cooled and thus, is also amorphous and retains theproperties of the amorphous sheet subjected to thermoforming. In certainapplications, however, it would be desirable to form a semi-crystallinepart having the shape of the desired mold. There remains a need forthermoforming processes that can produce a semi-crystalline part from anamorphous or pseudo-amorphous sheet thus producing a molded part whichexhibits increased thermal resistance, improved chemical resistance, andimprove mechanical properties in comparison to an amorphous orpseudo-amorphous part formed by conventional thermoforming processes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A depicts a thermoformed cup comprising PEKK produced according totraditional thermoforming processes and showing a transparency that isindicative of an amorphous part.

FIG. 1B depicts the thermoformed cup after being placed in an oven andheated to a temperature above the glass transition temperature of thepolymer to crystallize the part.

FIG. 2 illustrates a thermoformed cup manufactured from apseudo-amorphous sheet of PEKK according to an embodiment of a novelmethod disclosed herein and showing an opacity that is indicative of asemi-crystalline part.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide articles comprising apoly(aryl ketone), such as polyetherketoneketone (PEKK), and associatedmethods of making the same by novel thermoforming processes.

In some instances it is desirable to produce a thermoformed part that issemi-crystalline from a pseudo-amorphous polymer sheet. Similarly, insome instances it is desirable to significantly increase thecrystallinity of a previously molded part having a low crystallinitywithout distorting that part. According to an embodiment of the presentinvention, a method of producing a molded part comprises thermoformingat least one polymer comprising a pseudo-amorphous PAEK, such aspseudo-amorphous PEKK, under conditions effective to produce asemi-crystalline molded article.

According to an embodiment, a method of manufacturing a semi-crystallinearticle from at least one pseudo-amorphous polymer comprises a softeningstep in which at least one pseudo-amorphous polymer is heated to atemperature above the glass transition temperature of thepseudo-amorphous polymer without substantive crystallizing thepseudo-amorphous polymer to soften the pseudo-amorphous polymer and acrystallization step wherein the at least one pseudo-amorphous polymeris heated to a temperature above the glass transition temperature of thepseudo-amorphous polymer and below the melting temperature of thepseudo-amorphous polymer for a time sufficient to allow thepseudo-amorphous polymer to crystallize. During the softening step, itis conceivable that some crystallization may take place; however,preferably if crystallization occurs at the softening step, suchcrystallization is less than 10%, less than 5%, less than 2%, less than0.5%, less than 0.1%, or less than 0.001%. In some embodiments thepseudo-amorphous polymer may be placed on a mold during the softeningstep. In some embodiments the pseudo-amorphous polymer may be placed ona mold during the crystallization step before at least some of thecrystallization takes place. A semi-crystalline molded article may beformed on the mold. The semi-crystalline molded article may be opaque;however, in certain embodiments the semi-crystalline article may bealmost translucent or translucent.

In some embodiments, the pseudo-amorphous polymer may be a poly(arylketone) which may be selected from the group of polyetherketoneketone(PEKK), polyetheretherketone (PEEK), polyetherketone (PEK),polyetherketoneetherketoneketone (PEKEKK), and mixtures thereof,preferably PEKK. According to some embodiments, the pseudo-amorphouspolymer may be PEKK and may have a T:I isomer ratio within a range of50/50 to 85/15, preferably within a range of 65/35 to 75/25, such as aT:I isomer ratio of 70/30 (+/−2). According to other embodiments, thepseudo-amorphous polymer preferably is PEKK having a T:I ratio of about72:28, or about 71:29, or about 70:30, or about 69:31, or about 68:32.

In some embodiments, the pseudo-amorphous polymer may be in the form ofa sheet. In such embodiments, the sheet may be maintained on the moldduring the crystallization step for a time period in the range of onesecond to one minute or less, preferably forty seconds or less,optionally thirty seconds or less, twenty seconds or less, or tenseconds or less. In some embodiments, the pseudo-amorphous polymer, insheet form, may be transparent or semi-transparent.

In some embodiments, the mold may be heated on at least one side. Insome embodiments, the pseudo-amorphous polymer may be heated to atemperature within the range of 380° F. to 450° F., 380° F. to 440° F.,400° F. to 440° F., or 420° F. to 440° F., during the softening step.During the softening step, in some embodiments, the temperature may bemeasured using a non-contact method, such as by using a non-contactinfrared gun. In some embodiments, the mold and pseudo-amorphous polymermay be heated to a temperature in the range of 380° F. to 580° F., 400°F. to 500° F., 425° F. to 460° F., or 440° F. to 450° F. during thecrystallization step. In some embodiments, the temperature of thepseudo-amorphous polymer may be measured by using a probe within themold.

In some embodiments, the pseudo-amorphous polymer is placed on the moldduring or immediately prior to the crystallization step. In someembodiments, the pseudo-amorphous polymer may be placed onto the moldusing a vacuum subsequent to the softening step. In other embodiments,the pseudo-amorphous polymer is maintained on the mold during both thesoftening step and the crystallization step.

In some embodiments, the molded article produced may demonstrate atleast 1% improved crystallinity over the pseudo-amorphous polymer, atleast 5% improved crystallinity over the pseudo-amorphous polymer, andoptionally improved crystallinity over the pseudo-amorphous polymerwithin the range of 30-40%.

Other embodiments of the present invention are directed tosemi-crystalline molded articles prepared from sheets of at least onepseudo-amorphous polymer by a process of heating a sheet of at least onepseudo-amorphous polymer to a temperature above the glass transitiontemperature of the pseudo-amorphous polymer without substantivecrystallizing the pseudo-amorphous polymer to soften thepseudo-amorphous polymer and heating the sheet to a temperature abovethe glass transition temperature of the pseudo-amorphous polymer andbelow the melting temperature of the pseudo-amorphous polymer for a timesufficient to allow the pseudo-amorphous polymer to crystallize, whereinthe sheet is placed on a mold before at least some of thecrystallization takes place and is transformed into a semi-crystallinemolded article based upon the mold. Still other embodiments of thepresent invention are directed to semi-crystalline molded articlesprepared from a transparent or semi-transparent pseudo-amorphous polymerby a process of placing the pseudo-amorphous article onto a mold,heating the mold to a temperature above the glass transition temperatureof the pseudo-amorphous polymer and below the melting temperature of thepseudo-amorphous polymer for a time sufficient to allow thepseudo-amorphous polymer to crystallize and transforming thepseudo-amorphous article into the semi-crystalline molded article.

In embodiments directed to semi-crystalline molded articles, the atleast one pseudo-amorphous polymer may comprise a poly(aryl ketone),such as a PAEK selected from the group consisting ofpolyetherketoneketone (PEKK), polyetheretherketone (PEEK),polyetherketone (PEK), polyetherketoneetherketoneketone (PEKEKK), andmixtures thereof. In some embodiments, the semi-crystalline moldedarticle may comprise PEKK.

DETAILED DESCRIPTION OF THE INVENTION

Traditional thermoforming processes involve heating (e.g., in an oven) asheet of material, such as a plastic sheet, to a high temperature, suchas a temperature above the glass transition temperature of the materialand placing the heated sheet in contact with a cold (e.g., roomtemperature) mold to form a desired shape. The sheet may be stretchedinto or onto a mold using, for instance, a vacuum. When sheets ofpseudo-amorphous or amorphous materials are subjected to suchtraditional thermoforming processes, the thermoformed part is rapidlycooled on the mold, thus taking the form of the mold. The rapidly cooledthermoformed part retains the properties of the pseudo-amorphous oramorphous sheet subjected to thermoforming.

Thermoforming is useful, inter alia, to obtain molded articles comprisedhigh performance engineering plastics. These includepolyaryletherketones, such as PEKK, PEEK, PEK, and PEKEKK, in additionto other polymers such as polyamides, including high temperaturepolyamides. In many applications, it is desirable to improve theresistance to deformation of a molded part, such as those comprisingPEKK, for instance, by increasing the crystallinity of the molded part.

The applicants have developed novel methods for thermoforming articlescomprised of polyaryletherketones, such as poly(etherketoneketone)(PEKK), which produce parts with increased crystallinity, increasedthermal resistance, improved chemical resistance, and improvedmechanical properties over conventional thermoforming processes. Methodsof the present invention include using particular temperature profiles,heated molds, and additional processing conditions that enable thecrystallization of pseudo-amorphous polymers during the thermo-formingprocess.

As used herein, the term “article” may be used interchangeably with“part” or “object.” Exemplary articles of the present invention maycomprise (or may comprise parts of), for example, speaker cones, speakerspiders, back-end/burn in integrated circuit (IC) test sockets, IC wafercarriers, IC wafer handling tools, IC handling trays, Electronicpackaging, blister packaging, 3D electronic circuits, bearings, backingplates, bushings, sensors, switches, electronic housings, tubing,cylinders, cups, containers, container lids, satellite panels, mirrors,pump parts (e.g., impellers, stators, housings), aerospace parts (e.g.,cabinets, cabinet doors, sinks, control panels, toilets, passenger seatparts, including backs and pans), Compressed Natural Gas (CNG) orCompressed Liquefied Petroleum Gas (CLPG) composite tank forms,composite tooling forms, laminate protective cover films (e.g. forFFF/FDM/RFF tooling), and chemical storage containers. Exemplaryarticles of the present invention may comprise specialized parts ofintricate geometry with potential applications including, but notlimited to, aerospace, aircraft, oil and gas, electronics, building andconstruction, ducting, and high temperature containers, among others.

“Thermoforming” (encompassing “vacuum forming”), as used herein and inthe art, comprises heating a sheet of material to a pliable temperature(e.g., in an oven) and forming the heated sheet onto a cold mold (e.g.,a room temperature mold). The heated sheet may be stretched onto or overthe mold using a vacuum and may cool thereon resulting in a moldedarticle.

As used herein, the “sheet” or “film” that is thermoformed refers tolayers or membranes, which are known to those of ordinary skill in theart. The term “sheet” or “film” may be used interchangeably with theterm “membrane” herein. The sheets or films may be adhered to asubstrate or completely independent therefrom. The sheets or films maybe non-porous, porous, microporous, etc., depending on the applicationand use. The thicknesses of the sheets and films are unlimited and maybe any suitable thickness. For example, the films may have a thicknessfrom about 6 microns to about 7000 microns, preferably: about 300microns or more, about 500 microns or more, and thicknesses greater than500 microns up to about 7000 microns. The thickness may be measured, forexample, using a standard micrometer.

As used herein, “pseudo-amorphous” polymers comprise polymers havingfrom 0 percent crystallinity to less than about seven percentcrystallinity as determined by X-ray diffraction. For example,pseudo-amorphous polymers as discussed herein may be below seven percentcrystallinity, preferably below five percent crystallinity, morepreferably below three percent crystallinity. As used herein,“semi-crystalline” polymers comprise polymers having at least threepercent crystallinity as determined by X-ray diffraction.Semi-crystalline polymers as discussed herein may comprise at least fivepercent crystallinity or at least seven percent crystallinity, with apreference of at least five percent crystallinity.

As used herein, each compound may be discussed interchangeably withrespect to its chemical formula, chemical name, abbreviation, etc. Forexample, PEKK may be used interchangeably with polyetherketoneketone.Additionally, each compound described herein, unless designatedotherwise, includes homopolymers and copolymers. The term “copolymers”is meant to include polymers containing two or more different monomersand can include, for example, polymers containing two, three or fourdifferent repeating monomer units.

As used herein and in the claims, the terms “comprising” and “including”are inclusive or open-ended and do not exclude additional unrecitedelements, compositional components, or method steps. Accordingly, theterms “comprising” and “including” encompass the more restrictive terms“consisting essentially of” and “consisting of.”

According to an aspect of the present invention, a method ofmanufacturing a semi-crystalline article comprises a softening step ofheating at least one pseudo-amorphous polymer to a temperature above theglass transition temperature of the pseudo-amorphous polymer withoutsubstantively crystallizing the pseudo-amorphous polymer to soften thepseudo-amorphous polymer and a crystallization step of heating the atleast one pseudo-amorphous polymer to a temperature above the glasstransition temperature of the pseudo-amorphous polymer and below themelting temperature of the pseudo-amorphous polymer for a timesufficient to allow the pseudo-amorphous polymer to crystallize. Thepseudo-amorphous polymer may be placed on a mold during either thesoftening step or the crystallization step before at least some of thecrystallization takes place and a semicrystalline molded article may beformed using the mold.

In embodiments, the “at least one polymer” that is subjected to themethods disclosed herein may comprise, consist essentially of, orconsist of at least at least one poly(aryl ketone), preferably PEKK.Poly(aryl ketones) are intended to encompass all homopolymers andcopolymers (including, e.g., terpolymers) and the like. In oneembodiment, the poly(aryl ketone) is selected from the group consistingof polyetherketonketon (PEKK), polyetheretherketone (PEEK),polyetherketon (PEK), polyetherketoneetherketoneketone (PEKEKK), andmixtures thereof. The at least one polymer may optionally include morethan one polyaryletherketone. In embodiments, the “at least one polymer”may comprise, consist essentially of, or consist of at least onepolyamide. The at least one pseudo-amorphous polymer may consistessentially of a specific polymer when the specific polymer is, forinstance, at least 95%, at least 98%, at least 99%, or at least 99.9% byweight of the at least one pseudo-amorphous polymer.

In an exemplary embodiment, the poly(aryl ketone) comprises, consistsessentially of, or consists of polyetherketoneketone (PEKK).Polyetherketoneketones suitable for use in the present invention maycomprise or consist essentially of repeating units represented by thefollowing formulas I and II:

-A-C(═O)-B-C(═O)—  I

-A-C(═O)-D-C(═O)—  II

where A is a p,p′-Ph-O-Ph- group, Ph is a phenylene radical, B isp-phenylene, and D is m-phenylene. The Formula I:Formula II (T:I) isomerratio in the polyetherketoneketone can range from 100:0 to 0:100. Theisomer ratio may be easily varied as may be desired to achieve a certainset of properties, e.g., by varying the relative amounts of thedifferent monomers used to prepare the polyetherketoneketone. Generallyspeaking, a polyetherketoneketone having a relatively high FormulaI:Formula II ratio will be more crystalline than a polyetherketoneketonehaving a lower Formula I:Formula II ratio. Thus, the T:I ratio may beadjusted so as to provide an amorphous (non-crystalline)polyetherketoneketone or a more crystalline polyetherketoneketone, asdesired. In one embodiment, a polyetherketoneketone having a T:I isomerratio of from about 50:50 to about 90:10 may be employed.

For example, the chemical structure for a polyetherketoneketone with allpara-phenylene linkages [PEKK(T)] may be represented by the followingformula III:

The chemical structure for a polyetherketoneketone with onemeta-phenylene linkage in the backbone [PEKK(I)] may be represented bythe following formula IV:

The chemical structure for a polyetherketoneketone with perfectlyalternating T and I isomers, e.g., a homopolymer having 50% chemicalcompositions of both T and I [PEKK(T/I)] may be represented by thefollowing formula V:

The poly(aryl ketones) may be prepared by any suitable method, which iswell known in the art. For example, a poly(aryl ketone) may be formed byheating a substantially equimolar mixture of at least one bisphenol andat least one dihalobenzoid compound or at least one halophenol compound.The polymer may be amorphous, pseudo-amorphous, or crystallized, whichcan be controlled through synthesis of the polymer. The polymer(s)implemented in embodiments disclosed herein are preferably amorphous orpseudo-amorphous. Additionally, the polymer(s) may also be of anysuitable molecular weight and may be functionalized or sulfonated, ifdesired. In one embodiment, the polymer(s) undergo sulfonation or anyexample of surface modification known to one skilled in the art.

Suitable polyetherketoneketones are available from several commercialsources under various brand names. For example, polyetherketoneketonesare sold under the brand name KEPSTAN® polymers by Arkema Inc., such asfor example KEPSTAN 7000 and 7002. A variety of polyetherketoneketonepolymers are manufactured and supplied by Arkema.

In some embodiments, pseudo-amorphous PEKK polymer having a T:I ratio ofabout 72:28, or 71:29, or 70:30, or 69:31, or 68:32, or 67:33, or morepreferably 70:30, or 69:31, or 68:32 is used to provide extrusions (e.g.sheets which may be a production of extrusion cut to size) having adesirable thickness or thinness. In other embodiments, the PEKK polymermay have a viscosity at 360° C. of at least 400 Pa·s at 100 s−1 asmeasured by parallel plate rheometer. Use of such PEKK polymer enablesextrusions having a thickness of less than 10 mm, or between about 5 to0.1 mm, or no greater than 5 mm. Alternatively, use of such PEKKpolymers enables extrusions having a thickness of at least 0.5 mm orbetween 0.5 to about 10 mm, or at least greater than about 1 mm.

The amorphous or pseudo-amorphous polymers used in embodiments disclosedherein may include other polymers, in addition to the poly(aryl ketone).In one embodiment, the other polymers share similar melting points, meltstabilities, etc. and are compatible by exhibiting complete or partialmiscibility with one another. In particular, other polymers exhibitingmechanical compatibility with the poly(aryl ketone) may be added to thecomposition. It is also envisioned, however, that the polymers need notbe compatible with the poly(aryl ketone). The other polymers mayinclude, for example, polyamides (such as polyamide 11 and polyamide 12commercially available from Arkema under the name Rilsan,poly(hexamethylene adipamide) or poly(ε-caproamide)); fluorinatedpolymers (such as PVDF, PTFE and FEP); polyimides (such aspolyetherimide (PEI), thermoplastic polyimide (TPI), andpolybenzimidazole (PBI)); polysulfones/sulfides (such as polyphenylenesulfide (PPS), polyphenylene sulfone (PPSO₂), polyethersulfone (PES),and polyphenylsulfone (PPSU)); poly(aryl ethers); and polyacrylonitrile(PAN). In one embodiment, the other polymers include polyamide polymersand copolymers, polyimide polymers and copolymers, etc. Polyamidepolymers may be particularly suitable in high temperature applications.The additional polymers may be blended with the poly(aryl ketone) byconventional methods.

The amorphous or pseudo-amorphous polymers used in embodiments disclosedherein may also include additional component(s), such as filler(s) oradditive(s), to achieve specific properties desirable in particularapplications, such as core-shell impact modifiers; fillers orreinforcing agents, such as glass fibers; carbon fibers; plasticizers;pigments or dyes; thermal stabilizers; ultraviolet light stabilizers orabsorbers; antioxidants; processing aids or lubricants; flame retardantsynergists, such as Sb₂O₃, zinc borate, and the like; or mixturesthereof. These components may optionally be present, for example, in anamount of about 0.1 weight percent to about 70 weight percent based onthe total weight of the composition from which a polymer sheet orarticle (used to form a semi-crystalline article of disclosedembodiments) is formed (e.g., based on the total weight of a “dope”solution used to form a film, etc.).

Suitable fillers may include fibers, powders, flakes, etc. For examples,fillers may include at least one of carbon nanotubes, carbon fibers,glass fibers, polyamide fibers, hydroxyapatite, aluminum oxides,titanium oxides, aluminum nitride, silica, alumina, barium sulfates,grapheme, graphite, etc. The size and shape of the fillers are also notparticularly limited. Such fillers may be optionally present in anamount from about 0.1 weight percent to about 70 weight percent, or fromabout 10 weight percent to about 70 weight percent (based on a totalweight of the composition from which a polymer sheet or article used indisclosed embodiments is formed).

Methods of manufacturing a semi-crystalline article from at least onepseudo-amorphous polymer are based, in part, on improvements totraditional thermoforming methods. Traditional thermoforming methods inwhich a pseudo-amorphous or amorphous starting material is used yieldpseudo-amorphous or amorphous molded articles. The crystallinity ofthese pseudo-amorphous or amorphous molded articles cannot be enhancedby heating the molded articles (e.g., in an oven) subsequent to thetraditional thermoforming process without deformation.

FIG. 1A depicts a cup produced by subjecting a pseudo-amorphous PEKK totraditional thermoforming methods. The pseudo-amorphous PEKK film washeated to a temperature above the glass transition temperature of thePEKK and then placed onto a 25° C. mold. As can be seen from the figure,the resulting molded cup exhibits transparency which is indicative of anamorphous part.

Subsequent to production of the pseudo-amorphous part depicted in FIG.1A, the part was placed in an oven and heated above the glass transitiontemperature of the PEKK to crystallize the part. The result of thecrystallization step is depicted in FIG. 1B. As can be seen from thefigure, the material previously molded into a cup form is opaque,indicative of a crystalline article; however, the cup of FIG. 1A did notmaintain its thermoformed structure.

Embodiments disclosed herein comprise methods of manufacturing asemi-crystalline article from a pseudo-amorphous or amorphous polymersheet without distorting the formed article. Other embodiments disclosedherein comprise methods of manufacturing a semi-crystalline article froma previously formed pseudo-amorphous or amorphous polymer articlewithout distorting the formed article. Depicted in FIG. 2 is asemi-crystalline article manufactured from a pseudo-amorphous PEKKsubjected to an embodiment of a method disclosed herein. As can beobserved, the molded cup of FIG. 2 demonstrates opacity indicative of asemi-crystalline article.

Methods of manufacturing a semi-crystalline article disclosed herein maycomprise at least a crystallization step wherein at least onepseudo-amorphous polymer is heated to a temperature above the glasstransition temperature of the pseudo-amorphous polymer and below themelting temperature of the pseudo-amorphous polymer for a timesufficient to allow the pseudo-amorphous polymer to crystallize whilethe pseudo-amorphous polymer is on a mold. In some embodiments, thepseudo-amorphous polymer that is heated on the mold is a cold,pre-formed article having a shape similar to that of the mold.

In some embodiments, the method comprises a softening step in which atleast one pseudo-amorphous polymer is heated to a temperature above theglass transition temperature of the pseudo-amorphous polymer withoutsubstantive crystallizing the pseudo-amorphous polymer to soften thepseudo-amorphous polymer and a crystallization step wherein the at leastone pseudo-amorphous polymer is heated to a temperature above the glasstransition temperature of the pseudo-amorphous polymer and below themelting temperature of the pseudo-amorphous polymer for a timesufficient to allow the pseudo-amorphous polymer to crystallize. In someembodiments the pseudo-amorphous polymer may be placed on a mold duringthe softening step. In some embodiments the pseudo-amorphous polymer maybe placed on a mold during the crystallization step before at least someof the crystallization takes place. A semi-crystalline molded articlemay be formed on the mold.

In some embodiments, the pseudo-amorphous polymer may be a poly(arylketone) which may be selected from the group of polyetherketoneketone(PEKK), polyetheretherketone (PEEK), polyetherketone (PEK),polyetherketoneetherketoneketone (PEKEKK), and mixtures thereof,preferably PEKK. According to some embodiments, the pseudo-amorphouspolymer may be PEKK and may have a T:I isomer ratio within a range of50/50 to 80/20. In some embodiments, the pseudo-amorphous polymer mayhave a T:I isomer ratio of 70/30 (+/−2). In some embodiments, thepseudo-amorphous polymer does not include a nucleating agent.

In some embodiments, the softening step may be performed in an oven(e.g., similar to an indexing step performed in traditionalthermoforming methods). In some embodiments, subsequent to the softeningstep, the pseudo-amorphous polymer may be vacuum pulled onto a heatedmold and maintained on the mold for a period of time. In someembodiments, subsequent to placing the pseudo-amorphous polymer onto theheated mold, the pseudo-amorphous polymer may be subjected to a coolingprocess (e.g., using a fan). In some embodiments, the polymer may beheld on the mold by the vacuum for a period of thirty to sixty seconds.In some embodiments, the cooling process may begin, e.g., thirty secondsafter the beginning of the crystallization step. In other embodiments,the cooling process may begin, e.g., forty seconds after the beginningof the crystallization step. In some embodiments, the time period fromwhich the starting material is subjected to the softening,crystallization, and cooling steps (i.e., the “total cycle time”) isless than one minute. In some embodiments, the total cycle time isaround 90 seconds. In some embodiments, the total cycle time is lessthan 90 seconds.

In some embodiments, the pseudo-amorphous polymer may be in the form ofa sheet. In such embodiments, the sheet may be maintained on the moldduring the crystallization step for a time period within the range ofabout one second to about one minute. For instance, the sheet may bemaintained on the mold during the crystallization step for a time periodof: five minutes or less, one minute or less, forty seconds or less,thirty seconds or less, twenty seconds or less or ten seconds or less.In some embodiments, the pseudo-amorphous polymer, whether in sheet ormolded form, may be transparent or semi-transparent.

The temperature to which the pseudo-amorphous polymer is heated in thesoftening step will be dependent upon the pseudo-amorphous polymer used.In some embodiments, the pseudo-amorphous polymer may be heated to atemperature within the range of 380° F. to 415° F. during the softeningstep.

In some embodiments, the mold may be heated on at least one side. Insome embodiments the mold is heated on two sides. The mold may be, forexample, a female mold, a male mold, a two-piece mold, etc.

In some embodiments, during crystallization, additional or secondaryheating may be applied to the side of a PEKK sheet that is not incontact with the hot mold, especially for thicker sheets.

The mold may be heated, e.g., by implementing electric cartridgeheaters. The mold and/or polymer on the mold may be heated, in othermanners, e.g., infrared heating, etc. A temperature of the mold may bemeasured by using, e.g., a thermocouple. The mold may be heated to andmaintained at a temperature or within a temperature range during thecrystallization step. The temperature or temperature range within whichthe mold is maintained will be dependents upon the pseudo-amorphouspolymer used. In some embodiments, the mold may be heated to atemperature in the range of 440° F. to 450° F. during thecrystallization step.

In some embodiments, the pseudo-amorphous polymer is placed on the moldduring or immediately prior to the crystallization step. In someembodiments, the pseudo-amorphous polymer may be placed onto the moldusing a vacuum subsequent to the softening step. In other embodiments,the pseudo-amorphous polymer is maintained on the mold during both thesoftening step and the crystallization step.

In some embodiments, the molded article produced may demonstrate atleast 1% (absolute) increased crystallinity over the pseudo-amorphouspolymer, at least 5% increased crystallinity over the pseudo-amorphouspolymer, and optionally increased crystallinity over thepseudo-amorphous polymer within the range of 30-40%. In someembodiments, the crystallinity of the semi-crystalline molded articlemay be at least 10%, at least 15%, preferably at least 20%, morepreferably at least 30% or greater. Absolute as used herein means that,for example, a 1% increase of a starting material at 5% crystallinityresults in at least 6%, or optionally more, crystallinity.

Crystallinity of the molded article may be inferred based upon, e.g.,the appearance of the molded article. In some embodiments, asemi-crystalline molded article will have an opaque appearance.Crystallinity of the molded article may be measured, e.g., by X-raydiffraction (XRD). Crystallinity of the molded article may also bemeasured, e.g., by differential scanning calorimetry (DSC). Forinstance, X-ray diffraction data may be collected with copper K-alpharadiation at 0.5 deg/min for two-theta angles ranging from 5.0° to60.0°. The step size used for data collection should be 0.05° or lower.The diffractometer optics should be set as to reduce air scattering inthe low angle region around 5.0° two-theta. Crystallinity data may becalculated by peak fitting X-ray patterns and taking into accountcrystallographic data for the polymer of interest. A linear baseline maybe applied to the data between 5° and 60°.

Similarly, crystallinity of the pseudo-amorphous polymer may be inferredbased upon, e.g., the appearance of the pseudo-amorphous polymer. Insome embodiments, a pseudo-amorphous polymer will have a translucent oralmost translucent appearance. Crystallinity of the pseudo-amorphouspolymer may be measured, e.g., by X-ray diffraction (XRD) as describedabove, differential scanning calorimetry (DSC), etc.

Other embodiments of the present invention are directed tosemi-crystalline molded articles prepared from sheets of at least onepseudo-amorphous polymer by a process of heating a sheet of at least onepseudo-amorphous polymer to a temperature above the glass transitiontemperature of the pseudo-amorphous polymer without substantivecrystallizing the pseudo-amorphous polymer to soften thepseudo-amorphous polymer and heating the sheet to a temperature abovethe glass transition temperature of the pseudo-amorphous polymer andbelow the melting temperature of the pseudo-amorphous polymer for a timesufficient to allow the pseudo-amorphous polymer to crystallize, whereinthe sheet is placed on a mold before at least some of thecrystallization takes place and is transformed into a semi-crystallinemolded article based upon the mold. Still other embodiments of thepresent invention are directed to semi-crystalline molded articlesprepared from a transparent or semi-transparent pseudo-amorphous polymerby a process of placing the pseudo-amorphous article onto a mold,heating the mold to a temperature above the glass transition temperatureof the pseudo-amorphous polymer and below the melting temperature of thepseudo-amorphous polymer for a time sufficient to allow thepseudo-amorphous polymer to crystallize and transforming thepseudo-amorphous article into the semi-crystalline molded article.

In embodiments directed to semi-crystalline molded articles, the atleast one pseudo-amorphous polymer may comprise a poly(aryl ketone),such as a PAEK selected from the group consisting ofpolyetherketoneketone (PEKK), polyetheretherketone (PEEK),polyetherketone (PEK), polyetherketoneetherketoneketone (PEKEKK), andmixtures thereof. In some embodiments, the semi-crystalline moldedarticle may comprise PEKK.

In one preferred embodiment, during the crystallization step, certainselective or predetermined areas of the part may remain amorphous. Forexample, during infrared heating of a mold, the infrared heating may becarried out by selectively cutting the infrared source using a mask, themask being placed between the infrared source and the surface of thethermoformed sheet. The so-obtained amorphous areas may be used to carryout additional forming or welding steps. In addition, the amorphous areamay be, for example, thermoformed in a second or additional step.Preferably, after this second or additional thermoforming step, a finalobject is fully or substantially fully crystallized.

The amorphous area also can be welded using conventional weldingtechniques such as laser welding, ultrasonic welding, and hot plates soas to either laser weld multiple components into an assembly or to addfunctionalities to the thermoformed part. In the former case, an exampleof application may consist in thermoforming a loud speaker cone and weldthe cone to the support spider, thus eliminating the use of adhesives.Preferably, after welding, the final part is fully or substantiallyfully crystallized.

Aspects of the disclosure include:1. A method of manufacturing a semi-crystalline article from at leastone pseudo-amorphous polymer comprising: as a softening step, heating atleast one pseudo-amorphous polymer to a temperature above the glasstransition temperature of the pseudo-amorphous polymer thepseudo-amorphous polymer to soften the pseudo-amorphous polymer; as acrystallization step, heating the at least one pseudo-amorphous polymerto a temperature above the glass transition temperature of thepseudo-amorphous polymer and below the melting temperature of thepseudo-amorphous polymer for a time sufficient to allow thepseudo-amorphous polymer to crystallize; placing the pseudo-amorphouspolymer on a mold during either the softening step or thecrystallization step before the crystallization takes place; and formingan semi-crystalline molded article, wherein the pseudo-amorphous polymeris a poly aryl ether ketone (PAEK) selected from the group consisting ofpolyetherketoneketone (PEKK), polyetherketone (PEK),polyetherketoneetherketoneketone (PEKEKK), and mixtures thereof,preferably PEKK.2. The method of aspect 1, wherein the pseudo-amorphous polymer is PEKKand has a T:I isomer ratio in the range of 50150 to 85/15, preferably inthe range of 65/35 to 75/25, more preferably of about 70/30.3. The method of aspects 1 or 2, wherein the pseudo-amorphous polymer isin the form of a sheet.4. The method of aspect 3, wherein the sheet has a thickness fromgreater than 300 microns up to 7000 microns.5. The method of any of aspects 1-4, wherein the sheet is obtained onthe mold during the crystallization step for a time period of one minuteor less, optionally thirty seconds or less or twenty seconds or less.6. The method of any of aspects 1-5, wherein the mold is heated on oneside.7. The method of any of aspects 1-6, wherein the mold is heated to atemperature in the range of 380° F. to 550° F., optionally 400° F. to500° F., 425° F. to 460° F., or 440° F. to 450° F.8. The method of any of aspects 1-7, wherein during the softening step,the pseudo-amorphous polymer is heated to a temperature within the rangeof 380° F. to 450° F., optionally 400° F. to 440° F. or 420° F. to 440°F.9. The method of any of aspects 1-8, wherein the molded article has anincreased crystallinity over the pseudo-amorphous polymer of at leastfive percent, at least ten percent, at least fifteen percent, at leasttwenty percent, at least thirty percent, preferably within the range ofthirty to forty percent.10. The method of any of aspects 1-9, wherein the sheet is placed ontothe mold by a vacuum subsequent to the softening step.11. A semi-crystalline molded article prepared from a sheet of at leastone pseudo-amorphous polymer, wherein the semi-crystalline moldedarticle is formed by a process of: heating a sheet of at least onepseudo-amorphous polymer to a temperature above the glass transitiontemperature of the pseudo-amorphous polymer to soften thepseudo-amorphous polymer, heating the sheet to a temperature above theglass transition temperature of the pseudo-amorphous polymer and belowthe melting temperature of the pseudo-amorphous polymer for a timesufficient to allow the pseudo-amorphous polymer to crystallize; placingthe sheet on a mold before the crystallization takes place; andtransforming the sheet into the semi-crystalline molded article, whereinthe pseudo-amorphous polymer is a poly aryl ether ketone (PAEK) selectedfrom the group consisting of polyetherketoneketone (PEKK),polyetherketone (PEK), polyetherketoneetherketoneketone (PEKEKK), andmixtures thereof, preferably PEKK.12. A method of manufacturing an article according to aspect 1, whereincertain or pre-selected areas of the article are remain amorphous(non-crystalline) to enable an additional thermal forming or weldingstep.

The following examples are provided to describe properties andembodiments of the invention in greater detail and are intended toillustrate, not limit, the invention.

EXAMPLES Example 1—Thermoforming Conditions for PEKK Film

Films of pseudo-amorphous Kepstan™ 7002 PEKK having a thickness of 0.020inches were heated in an oven to index temperatures in the range of 380°F. to 415° F. The film had a T:I ratio of 70/30, a T_(g) of 344° F. anda T_(m) of 630° F. The film did not exhibit any measurable crystallinitywhen analyzed by X-ray diffraction, confirming they arepseudo-amorphous. After indexed, the films were removed from the ovenand a vacuum applied to pull the film onto a heated mold and hold it inplace thereon. The films were held on the mold for time periods rangingfrom 40 seconds to 60 seconds. The mold temperature used was in therange of 425° F. to 450° F. Cooling of the crystallized article formedon the mold was accomplished by applying a fan to the article. For thevarious films, the fan was turned on thirty seconds or forty secondsafter the indexed film was removed from the oven and placed on the mold.The results of the experiments nm are provided in Table 1.

TABLE 1 Part Mold Temp Index Temp Vacuum Time Fan Delay No. (° F.) (°F.) (s) (s) 1 440 390 40 30 2 440 380 40 30 3 440 390 40 30  4* 425 38040 30 5 440 390 50 30 6 450 400 50 40 7 450 415 60 40 8 450 400 60 40

In the above table, the fan delay represents the total time that thepart was allowed to crystallize on the heated mold prior to coolingbeing initiated. The total cycle time for films which formed the mostideal parts was 90 seconds. The total cycle time is a time period atwhich the cold sheet entered the oven to be indexed to the time that thepart is considered “finished” (i.e., the part is formed and sufficientlycooled).

The films used in the experiment were transparent prior to indexing andsubsequent to indexing, indicative of a pseudo-amorphous or amorphousfilm. When placed on the heated mold, the portion of the film in contactwith the mold became opaque in appearance, whereas portions of the filmnot in contact with the mold (i.e., that were more rapidly cooled)remained transparent or translucent in appearance. The observed opacityof the molded part is indicative of crystallinity. Thus, thepseudo-amorphous films were formed into crystalline parts.

Notably, Part No. 4, marked by an asterisk above, became stuck in themold and thus was disfigured in comparison to part nos. 1-3 and 5-8.Part 4 demonstrated low crystallinity which can be attributed, at leastin part, to the relatively cold temperature of the mold used to formPart 4 as compared with the mold temperature implemented to form parts1-3 and 5-8.

Example 2—Crystallinity Measurements for Thermoformed PEKK Film

Films of pseudo-amorphous Kepstan™ 7002 PEKK having a thickness of 0.020inches were heated in an oven to index temperatures in the range of 195°C. to 225° C. The film had a T:I ratio of 70/30, a T_(g) of 344° F. anda T_(m) of 630° F. The film did not exhibit any measurable crystallinitywhen analyzed by X-ray diffraction, confirming they arepseudo-amorphous. After indexed, the films were removed from the ovenand a vacuum applied to pull the film onto a heated mold and hold it inplace thereon. The films were held on the mold for a period of 80seconds. The mold temperature used was in the range of 195° C. to 285°C. Cooling of the crystallized article formed on the mold wasaccomplished by applying a fan to the article. For the various films,the fan was turned on 50 seconds after the indexed film was removed fromthe oven and placed on the mold. The results of the experiments run areprovided in Table 2.

TABLE 2 Index Mold Crystallinity of Temp (° C.) Temp (° C.) thermoformedpart (%) 195 195 7 195 205 9 195 253 25 195 285 26 210 195 9 210 205 17225 195 21 225 205 24 225 225 25 225 243 25 225 265 26 225 285 24

The films used in the experiment were transparent prior to indexing andsubsequent to indexing, indicative of a pseudo-amorphous or amorphousfilm. When placed on the heated mold, the portion of the film in contactwith the mold became opaque in appearance, whereas portions of the filmnot in contact with the mold (i.e., that were more rapidly cooled)remained transparent or translucent in appearance. The observed opacityof the molded part is indicative of crystallinity.

The semi-crystalline composition of the molded part was verified byX-ray diffraction measurements. X-ray diffraction data was collectedwith copper K-alpha radiation at 0.5 deg/min for two-theta anglesranging from 5.0° to 60.0°. The step size used for data collection was0.05° or lower. The diffractometer optics were set to reduce airscattering in the low angle region around 5.0° two-theta.

Crystallinity data was calculated by peak fitting the X-ray patterns andtaking into account crystallographic data for PEKK forms I and II (asdescribed by Gardner et al. in POLYMER, 1992, Vol. 33, No. 12, pp.2483-2495). A linear baseline was applied to the data between 5.0° and60.0°.

The experimental data in Table 2 illustrates semi-crystalline articleshaving a crystallinity of 7% to 26% as measured by XRD. Additionally,the application of the described method of Example 2 to pseudo-amorphousKepstan™ 7002 enables a broad range of working conditions, asillustrated in Table 2.

Example 3—Thermoforming Conditions for PEKK Sheets

Sheets of pseudo-amorphous Kepstan™ 7002 PEKK having a thickness of0.080 inches were heated in an oven to index temperatures in the rangeof 380° F. to 420° F. The film had a T:I ratio of 70/30, a T_(g) of 344°F. and a T_(m) of 630° F. After indexed, the sheets were removed fromthe oven and a vacuum applied to pull the film onto a heated mold andhold it in place thereon. The sheets were held on the mold for timeperiods ranging from 90 seconds to 150 seconds. The mold temperatureused was in the range of 425° F. to 482° F. Cooling of the crystallizedarticle formed on the mold was accomplished by applying a fan to thearticle. For the various sheets, the fan was turned on 70 seconds to 120seconds after the indexed film was removed from the oven and placed onthe mold. A summary of the conditions to thermoform sheets are providedin Table 3. All of the sheets

TABLE 3 Oven Mold Index Vacuum Fan Part Preheat temp temp time Delay No.(° C.) (° C.) (° F.) (s) (s)  9 455 450 400 90 70 10 455 450 400 90 7011 478 450 420 120 90 12 464 464 410 120 90 13 473 464 410 150 120  14*437 464 400 150 120 *had heat applied to side of part not in contactwith the mold from a 250 w heat lamp.

The sheets used in the experiment were transparent prior to indexing andsubsequent to indexing, indicative of a pseudo-amorphous or amorphoussheet. When placed on the heated mold, the portion of the film incontact with the mold became opaque in appearance, whereas portions ofthe sheet not in contact with the mold (i.e., that were more rapidlycooled) remained transparent or translucent in appearance. The observedopacity of the molded part is indicative of crystallinity. Parts 9through 14 had an increasing degree of opacity in the section in contactwith the heated mold. Thus, the pseudo-amorphous sheets were formed intocrystalline parts. Thick sheets required longer time in contact with thehot mold and possibly additional heating applied to the side not incontact with a mold to produce a fully crystalline part.

What is claimed is:
 1. A method of manufacturing a semi-crystallinearticle from at least one pseudo-amorphous polymer using athermo-forming process, said method comprising: as a softening step,heating at least one pseudo-amorphous polymer having less than aboutseven % crystallinity and in sheet form to a temperature above the glasstransition temperature of the pseudo-amorphous polymer to soften thepseudo-amorphous polymer; as a crystallization step, heating the atleast one pseudo-amorphous polymer to a temperature above the glasstransition temperature of the pseudo-amorphous polymer and below themelting temperature of the pseudo-amorphous polymer for a timesufficient to allow the crystallinity of pseudo-amorphous polymer toincrease on a mold; placing the pseudo-amorphous polymer on the moldduring either the softening step or the crystallization step before theincrease in crystallization takes place; and forming an semi-crystallinemolded article wherein said crystallinity increases by at least 5%(absolute) crystallinity over the pseudo-amorphous polymer, wherein thepseudo-amorphous polymer comprises (i) poly aryl ether ketone (PAEK)selected from the group consisting of polyetherketoneketone (PEKK),polyetherketone (PEK), polyetherketoneetherketoneketone (PEKEKK), andmixtures thereof and (ii) another polymer selected from the groupconsisting of fluorinated polymers, polyimides, polysulfones, andpolysulfides.
 2. A method of manufacturing an article according to claim1, wherein the PAEK is PEKK.
 3. A method of manufacturing an articleaccording to claim 2, wherein the PEKK has a T:I isomer ratio within arange of 50/50 to 85/15.
 4. A method of manufacturing an articleaccording to claim 3, wherein the PEKK has a T:I isomer ratio of about70/30.
 5. A method of manufacturing an article according to claim 1,wherein the sheet has a thickness greater than about 300 microns.
 6. Amethod of manufacturing an article according to claim 1, wherein thesheet is maintained on the mold during the crystallization step for atime period of one minute or less.
 7. A method of manufacturing anarticle according to claim 1, wherein the sheet is maintained on themold during the crystallization step for a time period of thirty secondsor less.
 8. A method of manufacturing an article according to claim 1,wherein the sheet is maintained on the mold during the crystallizationstep for a time period of twenty seconds or less.
 9. A method ofmanufacturing an article according to claim 1, wherein the mold isheated on at least one side.
 10. A method of manufacturing an articleaccording to claim 10, wherein the mold is heated to a temperature inthe range of 380° F. to 550° F.
 11. A method of manufacturing an articleaccording to claim 11, wherein the pseudo-amorphous polymer is heated toa temperature within the range of 380° F. to 450° F. during thesoftening step.
 12. A method of manufacturing an article according toclaim 12, wherein the pseudo-amorphous polymer is placed on the moldimmediately prior to the crystallization step.
 13. A method ofmanufacturing an article according to claim 1, wherein the moldedarticle has at least a ten percent increased crystallinity over thepseudo-amorphous polymer.
 14. A method of manufacturing an articleaccording to claim 1, wherein the molded article has an increasedcrystallinity over the pseudo-amorphous polymer within a range of thirtyto forty percent.
 15. A method of manufacturing an article according toclaim 1, wherein the sheet is placed onto the mold by a vacuumsubsequent to the softening step.
 16. A method of manufacturing anarticle according to claim 2, wherein the PEKK has a T:I isomer ratio of70:30, or 69:31, or 68:32.
 17. A method of manufacturing an articleaccording to claim 2, wherein the PEKK has a T:I isomer ratio of 71:29or 72:28.
 18. A method of manufacturing an article according to claim 2,wherein the PEKK has a T:I ratio of 70:30 (+/−2) and/or wherein themolded article has at least a ten percent increased crystallinity overthe pseudo-amorphous polymer.
 19. A method of manufacturing an articleaccording to claim 1, wherein said another polymer is selected from thegroup consisting of polytetrafluoroethylene (PTFE) and fluorinatedethylene propylene (FEP).
 20. A method of manufacturing an articleaccording to claim 1, wherein said another polymer is selected from thegroup consisting of polyimides, polyetherimide (PEI), thermoplasticpolyimide (TPI) and polybenzimidazole (PBI).
 21. A method ofmanufacturing an article according to claim 1, wherein said anotherpolymer is selected from the group consisting of polysulfones andpolyphenylsulfone (PPSU).
 22. The method of manufacturing an articleaccording to claim 1, where the pseudo-amorphous polymer is a blend of(i) and (ii).